package org.bouncycastle.asn1.pkcs;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;

public class RSASSAPSSparams extends ASN1Encodable {
    private AlgorithmIdentifier hashAlgorithm;
    private AlgorithmIdentifier maskGenAlgorithm;
    private DERInteger saltLength;
    private DERInteger trailerField;

    // BEGIN android-changed
    public final static AlgorithmIdentifier DEFAULT_HASH_ALGORITHM = new AlgorithmIdentifier(
            OIWObjectIdentifiers.idSHA1, DERNull.INSTANCE);
    // END android-changed
    public final static AlgorithmIdentifier DEFAULT_MASK_GEN_FUNCTION = new AlgorithmIdentifier(
            PKCSObjectIdentifiers.id_mgf1, DEFAULT_HASH_ALGORITHM);
    public final static DERInteger DEFAULT_SALT_LENGTH = new DERInteger(20);
    public final static DERInteger DEFAULT_TRAILER_FIELD = new DERInteger(1);

    public static RSASSAPSSparams getInstance(Object obj) {
        if (obj == null || obj instanceof RSASSAPSSparams) {
            return (RSASSAPSSparams) obj;
        } else if (obj instanceof ASN1Sequence) {
            return new RSASSAPSSparams((ASN1Sequence) obj);
        }

        throw new IllegalArgumentException("unknown object in factory: "
                + obj.getClass().getName());
    }

    /**
     * The default version
     */
    public RSASSAPSSparams() {
        hashAlgorithm = DEFAULT_HASH_ALGORITHM;
        maskGenAlgorithm = DEFAULT_MASK_GEN_FUNCTION;
        saltLength = DEFAULT_SALT_LENGTH;
        trailerField = DEFAULT_TRAILER_FIELD;
    }

    public RSASSAPSSparams(AlgorithmIdentifier hashAlgorithm,
            AlgorithmIdentifier maskGenAlgorithm, DERInteger saltLength,
            DERInteger trailerField) {
        this.hashAlgorithm = hashAlgorithm;
        this.maskGenAlgorithm = maskGenAlgorithm;
        this.saltLength = saltLength;
        this.trailerField = trailerField;
    }

    public RSASSAPSSparams(ASN1Sequence seq) {
        hashAlgorithm = DEFAULT_HASH_ALGORITHM;
        maskGenAlgorithm = DEFAULT_MASK_GEN_FUNCTION;
        saltLength = DEFAULT_SALT_LENGTH;
        trailerField = DEFAULT_TRAILER_FIELD;

        for (int i = 0; i != seq.size(); i++) {
            ASN1TaggedObject o = (ASN1TaggedObject) seq.getObjectAt(i);

            switch (o.getTagNo()) {
                case 0:
                    hashAlgorithm = AlgorithmIdentifier.getInstance(o, true);
                    break;
                case 1:
                    maskGenAlgorithm = AlgorithmIdentifier.getInstance(o, true);
                    break;
                case 2:
                    saltLength = DERInteger.getInstance(o, true);
                    break;
                case 3:
                    trailerField = DERInteger.getInstance(o, true);
                    break;
                default:
                    throw new IllegalArgumentException("unknown tag");
            }
        }
    }

    public AlgorithmIdentifier getHashAlgorithm() {
        return hashAlgorithm;
    }

    public AlgorithmIdentifier getMaskGenAlgorithm() {
        return maskGenAlgorithm;
    }

    public DERInteger getSaltLength() {
        return saltLength;
    }

    public DERInteger getTrailerField() {
        return trailerField;
    }

    /**
     * <pre>
     * RSASSA-PSS-params ::= SEQUENCE {
     *   hashAlgorithm      [0] OAEP-PSSDigestAlgorithms  DEFAULT sha1,
     *    maskGenAlgorithm   [1] PKCS1MGFAlgorithms  DEFAULT mgf1SHA1,
     *    saltLength         [2] INTEGER  DEFAULT 20,
     *    trailerField       [3] TrailerField  DEFAULT trailerFieldBC
     *  }
     * 
     * OAEP-PSSDigestAlgorithms    ALGORITHM-IDENTIFIER ::= {
     *    { OID id-sha1 PARAMETERS NULL   }|
     *    { OID id-sha256 PARAMETERS NULL }|
     *    { OID id-sha384 PARAMETERS NULL }|
     *    { OID id-sha512 PARAMETERS NULL },
     *    ...  -- Allows for future expansion --
     * }
     * 
     * PKCS1MGFAlgorithms    ALGORITHM-IDENTIFIER ::= {
     *   { OID id-mgf1 PARAMETERS OAEP-PSSDigestAlgorithms },
     *    ...  -- Allows for future expansion --
     * }
     * 
     * TrailerField ::= INTEGER { trailerFieldBC(1) }
     * </pre>
     * 
     * @return the asn1 primitive representing the parameters.
     */
    public DERObject toASN1Object() {
        ASN1EncodableVector v = new ASN1EncodableVector();

        if (!hashAlgorithm.equals(DEFAULT_HASH_ALGORITHM)) {
            v.add(new DERTaggedObject(true, 0, hashAlgorithm));
        }

        if (!maskGenAlgorithm.equals(DEFAULT_MASK_GEN_FUNCTION)) {
            v.add(new DERTaggedObject(true, 1, maskGenAlgorithm));
        }

        if (!saltLength.equals(DEFAULT_SALT_LENGTH)) {
            v.add(new DERTaggedObject(true, 2, saltLength));
        }

        if (!trailerField.equals(DEFAULT_TRAILER_FIELD)) {
            v.add(new DERTaggedObject(true, 3, trailerField));
        }

        return new DERSequence(v);
    }
}
